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Willis was found guilty of attempted murder after attacking Ms Pearson with scissors and faces a lengthy prison sentence.

Outside the court, Ms Pearson said: "Every night you go to bed and you don't know what is going to happen and you constantly live in fear."

She said she would be making an official complaint to police about their lack of action.

Her father, Bernard Pearson, added: "Nobody could see in the police that the level of violence was rising, rising and rising."

Detective Inspector Mike Robison defended the way police had dealt with scores of reports of harassment during the five years in which Willis stalked his victim before the attack.

He said the force is carrying out an internal review under the auspices of the Independent Police Complaints Commission and will implement any lessons learned.

But following his conviction the full scale of cunning stalker Joseph Willis campaign of harrassment can now be revealed.

The former mechanic and self taught computer geek met Helen when she moved to a flat close to his at a supported housing project.

She had a history of problems with eating disorders and her flat in Exe Street, Exeter, was her first attempt at independent living, leaving her particularly vulnerable to his obsessive behaviour.

Willis had his own history on mental problems and was under the care of the psychiatric service throughout the five years in which he embarked on his campaign of stalking and harassment.

At first he posed as the perfect neighbour, befriending her parents when they made their regular visits from Crediton to see their daughter.

He offered to help her with household chores and she responded by inviting him to join a cycling group but their innocent friendship was to be shattered by a single petty misunderstanding.

Willis wanted to go and see a band called Carnaby Street who were playing at Topsham Football Club. He invited Helen and hoped she would give him a lift and a friend a lift in her car.

She did not like going out in the evenings and her Smart car only had two seats, so she told him she would text him if she was going.

He believed she had stood him up and his friendship turned instantly to a burning hatred which was to simmer for five years and increase gradually to the point where he went in search of her armed with a pair of scissors.

The next morning he got up early and intercepted her on her morning run, calling her mean and nasty and he followed this up with a letter to her parents denouncing her as a horrible person.

The stalking started within days with minor acts of vandalism against her home and car and silent phone calls.

Over the next five years it got progressively worse and she started keeping a diary in which she logged 125 different instances of harassment, ranging from nuisance calls to a dead cat being left on her doorstep.

The phone calls became so frequent Helen turned detective and walked around the streets of Exeter logging the numbers of all the call boxes so she could identify them to police when the silent or abusive calls were made.

She installed security grilles on her windows after they were smashed and cameras at her parents’ home in Fairfield Road, Crediton, which was also vandalised.

Police stepped up patrols and improved surveillance at her flat but Willis remained one step ahead of them by checking out and sidestepping each new security measure.

Helen and her family hired a private detective agency to trace the mystery stalker but they were no more successful than the police.

He succeeded in casting suspicion on Helen herself by telling neighbours that police believed she was damaging her own property as an attention seeking device.

After his arrest police found photos on his camera which showed how he had taken pictures of Helen’s flat and her parents’ home so he could check out the security measures.

The stalking had a profound effect on Helen, who was already vulnerable and as they years went by she felt increasingly insecure and frightened.

She described her existence as a living hell in which she was constantly worried about what would happen next. And with good cause.

She suspected Willis but had no proof and her fears were increased in the months before the scissors attack by two vile letters sent anonymously.

These called her fat, rat-faced, and worse, but what was really sinister about them was that they showed that her stalker had an intimate knowledge of her movements and lifestyle.

One referred to a trip she had made on her own to Dartmoor while the second spoke about her late night runs and warned her ‘watch your back’ – a chilling premonition of his attack.

The letters also made it clear her had searched her bins and one included a used sanitary towel as proof.

She later told police:”It was like a drip-drip effect. When I received the letters I was absolutely terrified. I literally felt I had to live within my four walls. The letter told me to watch my back and I thought he was going to kill me.”

Willis’ campaign of hate came to its horrific culmination just two months after the second letter was sent. Helen was never in any doubt that her attacker was the same man as had been stalking her.

Her first words after she had run to take refuge at her gym were:”I know who it was. It was my stalker.”

Once Willis was arrested, tests on his computer and camera proved beyond doubt he was the stalker. The two hate letters were found in his deleted files and there were scores of searches about her name.

There were also searches about her parents and about a support group for eating disorders which she had been part of.

Willis claimed the incriminating files had been transferred onto his laptop from second-hand hard drives he found in the street but his explanation made no technical sense.

He told the jury that during his attack it was Helen who had the scissors and had tried to stab him but his account was contradicted not only by her evidence but three independent witnesses and CCTV camera footage which showed him running behind her and reaching into his pocket for the scissors.

Recalling the attack, Ms Pearson said: "The first I knew about it was when I was stabbed in the back. I turned and saw it was Joe.

"I saw his eyes and he looked absolutely furious. The first blow pushed me to the floor and he kicked me and was trying to drag me along into the Catacombs. That was where it was going to end. I tried to get free. I felt another kick and stab from behind.

"I thought this is going to go on until I am dead. He was deranged and so evil. I had six stab wounds in total on my back.

"I remember seeing the scissors and turning my head and seeing them come down. I saw his eyes were full of murder. He definitely wanted me to die.

"I was struggling and screaming and pleading. I remember saying, “Please, Joe, no”. He never spoke to me throughout the whole thing."